Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210505031416.30128-1-saravanak@google.com> <20210505054838.GA22603@wunner.de>
In-Reply-To: <20210505054838.GA22603@wunner.de>
From:   Saravana Kannan <saravanak@google.com>
Date:   Wed, 5 May 2021 09:31:09 -0700
Message-ID: <CAGETcx9EnNKwq-KQ5dDifAV25jsJ3WCv6iqs7TqsAgXaUfFgbg@mail.gmail.com>
Subject: Re: [PATCH v1] spi: Don't have controller clean up spi device before
 driver unbind
To:     Lukas Wunner <lukas@wunner.de>
Cc:     Mark Brown <broonie@kernel.org>,
        Android Kernel Team <kernel-team@android.com>,
        linux-spi <linux-spi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, May 4, 2021 at 10:48 PM Lukas Wunner <lukas@wunner.de> wrote:
>
> On Tue, May 04, 2021 at 08:14:16PM -0700, Saravana Kannan wrote:
> > @@ -415,6 +421,7 @@ static int spi_remove(struct device *dev)
> >                                ERR_PTR(ret));
> >       }
> >
> > +     spi_cleanup(to_spi_device(dev));
> >       dev_pm_domain_detach(dev, true);
> >
> >       return 0;
>
> Unfortunately this doesn't look right:  spi_remove() is run on
> driver unbind of the spi_device.  With the above change,
> ->setup is called on spi_device addition and ->cleanup is called
> on unbind, which is obviously assymetric.  What can happen
> here is that a slave-specific controller_state is allocated on
> spi_device addition, then on unbind that controller_state is freed
> and on a subsequent rebind it won't be recreated because ->setup
> isn't run on spi_device ->probe.

Good point!

>
> As I've written yesterday, calling spi_cleanup() in
> spi_unregister_device() should be fine if you move it to the end
> of the function, but before the final put_device().  For that,
> you need to open code the calls to device_del() and put_device()
> that happen in device_unregister() so far.

Yeah, I saw that email after I sent out this patch. I'll send out a v2.

-Saravana